The maltohexaose-forming, Ca²⁺-independent α-amylase gene from Bacillus stearothermophilus (AmyMH) was efficiently expressed in Brevibacillus choshinensis SP3. To improve the production of AmyMH in B. choshinensis SP3, the temperature and initial pH of culture medium were optimized. In addition, single-factor and response surface methodologies were pursued to optimize culture medium. Addition of proline to the culture medium significantly improved the production of recombinant α-amylase in B. choshinensis SP3. This improvement may result from improved cellular integrity of recombinant B. choshinensis SP3 in existence of proline. Culture medium optimization resulted in an 8-fold improvement in α-amylase yield, which reached 1.72 × 10⁴ U·mL⁻¹. The recombinant α-amylase was applied to the production of maltose on a laboratory scale. A maltose content of 90.72%, which could be classified as an extremely high maltose syrup, could be achieved using 15% (m/v) corn starch as the substrate. This study demonstrated that the B. choshinensis SP3 expression system was able to produce substantial quantities of recombinant α-amylase that has potential application in the starch industry.

中文翻译：

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嗜热脂肪芽孢杆菌中形成麦芽六糖的α-淀粉酶在choshinensis短杆菌SP3中的高效表达及其在麦芽糖生产中的应用。

来自嗜热脂肪芽孢杆菌（AmyMH）的形成麦芽六糖的独立于Ca ^2+的α-淀粉酶基因在Choshinensis短杆菌SP3中得到有效表达。为了提高B. choshinensis SP3中AmyMH的产量，优化了培养基的温度和初始pH。另外，采用单因素和响应面方法来优化培养基。向培养基中添加脯氨酸显着改善了C. choshinensis SP3中重组α-淀粉酶的产生。这种改善可能是由于重组猪胆囊菌的细胞完整性得到改善SP3存在脯氨酸。培养基的优化导致α-淀粉酶产量提高了8倍，达到1.72×10 ⁴  U·mL ^-1。重组α-淀粉酶以实验室规模应用于麦芽糖的生产。使用15％（m / v）的玉米淀粉作为基质，可以达到90.72％的麦芽糖含量（可以归类为极高的麦芽糖糖浆）。这项研究表明，C。choshinensis SP3表达系统能够产生大量的重组α-淀粉酶，在淀粉工业中具有潜在的应用前景。